Historical records of orchid bees (Apidae: Euglossini) in Belém Endemism Center: species list of 92 years sampling

The distribution of most species occurs in delimited regions with unique characteristics called “centers of endemism”. In Eastern Amazon is located the Belém Endemism Center (BEC), one of the most intensely deforested in Brazilian Amazon. Here, we show information about orchid bee assemblages based on historical records from entomological collections. For each species, we calculated occurrence frequency and dominance, and we classified them in 3 statuses: common, intermediate or rare species. Curves of observed and estimated richness were built, based on Jackknife estimator. We found 1,257 specimens from 56 species, constituting records from 1917 to 2009, and one species is a new record for BEC. Higher number of specimens and species was concentrated in a few locations and surveys increased from the 70’s. The results suggest a high richness of orchid bees in the BEC, although this scenario is far from what is expected for the entire area. The high occurrence of rare species may be related to their low representativeness in the collections, and the proximity between the areas had favored samplings. Even so, the species list and the conservation status presented here may be useful information in studies comparing past and current orchid bee fauna, and, allied to data on bees’ responses to land use changes occurred in BEC over the years, can fit as a basis for defining priority areas for conservation.

A Jackknife Estimator of Variance for a Random Tessellated Stratified Sampling Design

Semisystematic sampling designs—in which a population area frame is tessellated into cells, and a randomly located sample is taken from each cell—affords random tessellated stratified (RTS) Horvitz–Thompson-type estimators. Forest inventory applications with RTS estimators are rare, possibly because of computational complexities with the estimation of variance. To reduce this challenge, we propose a jackknife estimator of variance for RTS designs. We demonstrate an application with a model-assisted ratio of totals estimator and data from the Danish National Forest Inventory. RTS estimators of standard error were, as a rule, smaller than comparable estimates obtained under the assumption of simple random sampling. The proposed jackknife estimator performed well.

Bootstrap, Jackknife and COLS: Bias and Mean Squared Error in Estimation of Autoregressive Models

We compare a number of bias-correction methodologies in terms of mean squared error and remaining bias, including the residual bootstrap, the relatively unexplored Quenouille jackknife, and methods based on analytical approximation of moments. We introduce a new higher-order jackknife estimator for the AR(1) with constant. Simulation results are presented for four different error structures, including GARCH. We include results for a relatively extreme situation where the errors are highly skewed and leptokurtic. It is argued that the bootstrap and analytical-correction (COLS) approaches are to be favoured overall, though the jackknife methods are the least biased. We find that COLS tends to have the lowest mean squared error, though the bootstrap also does well.

The status of the Endangered Persian leopard Panthera pardus saxicolor in Bamu National Park, Iran

We describe the use of camera-trapping with capture-recapture, occupancy and visitation rate modelling to study the size, demographic structure and distribution of the Persian leopard Panthera pardus saxicolor in Bamu National Park, southern Iran. A total sampling effort of 1,012 trap-nights yielded photo-captures of four adults, two subadult individuals and a cub over 21 sampling occasions. The leopard population size estimated by the M(h) model and jackknife estimator was 6.00 ± SE 0.24 individuals. This gives a density of 1.87 ± SE 0.07 leopards per 100 km2. Detection probability was constant and low and, as a result, estimated occupancy rate was significantly higher than that predicted from photographic capture sites alone. Occupancy was 56% of the protected area and visitation rates were 0.01–0.05 visits per day. The most imminent threats to leopards in Bamu are poaching and habitat fragmentation.

Estimation in an Exponential Distribution with Common Location and Scale Parameters

We consider several point estimators including the jackknife estimator for the estimation of the common location and scale parameters and the right tail probability in an exponential distribution . Several interval estimators of the common location and scale parameters arc also obtained.

A Method to Treat Some Dynamical Statistical Models

In this paper we present a method for the estimation of the parameters of models described by a nonlinear system of differential equations: we study the maximum likelihood estimator and the jackknife estimator for parameters of the system and for the covariance matrix of the state variables and we seek possible linear relations between parameters. We take into account the difficulty due to the small number of observations. The optimal experimental design for this kind of problem is determined. We give an application of this method for the glucose metabolism of goats.